It was cenx saying that the Reaver Shark is much rarer now.
The problem is, if something's overpowered, making it "rarer" isn't going to help much, especially when it's something that can easily be spammed... like fishing.
If the devs want it fishable pre-hardmode, but don't want it sequence-breaking so much, then there are a couple of proper solutions, neither of which is "most players don't get to do this, but you're lucky or maybe you just put in your ten hours work". You can dial back the power, or put a real gate in front of it... or both: Suppose you fish up a NerfShark that can match a platinum pickaxe or so, but you can combine it with something to get the power of the current Reaver Shark. The obvious choices for the "something" fall along a scale: Meteorite bars, Evil ore/bars, Evil pickaxe (or just Scales/Samples), obsidian, or Hellstone ore/bars, depending when you want to allow it.
That said, I don't think having the Reaver Shark be overpowered is that much of a problem -- yeah it's mildly sequence-breaking, but it's part of a pattern where fishing allows for limited sequence breaking. Other pattern members are the Rockfish, Sawtooth Shark, and the Falcon Blade (IMHO overshadowing the more direct Swordfish). And fishing for biome crates can get you some of their chest items.
The other thing is, there actually is a gate of sorts there: You need to be able to get to the ocean (always across evil, and perhaps jungle as well), get bait, and survive fishing out there long enough to snag an RS (which also needs some fishing power). You
can do that with raw skill and guts, but most folks will take a little more time to de-crunchify themselves first.
It's not as bright a line as "I beat EOC", but it's something.